Selection of clinical laboratory tests in renal diseases. Evaluation of the results of a study of non-protein nitrogen containing substances – advantages and disadvantages.
The routine blood and urine tests listed below may provide the first indication of a kidney problem or may be ordered if chronic kidney disease (CKD) is suspected due to a person's signs and symptoms. These tests reflect how well the kidneys are removing excess fluids and wastes.
Creatinine clearance: 1.33-3.00 ml/s
High creatinine clearance values can be caused by strenuous exercise, muscle injury (especially crushing injuries), burns, carbon monoxide poisoning, hypothyroidism, and pregnancy.
Low creatinine clearance. Low creatinine clearance levels can mean serious kidney damage is present. Kidney damage can be from conditions such as a life-threatening infection, shock, cancer, low blood flow to the kidneys, or urinary tract blockage. Other conditions, such as heart failure dehydration, and liver disease (cirrhosis), can also cause low creatinine clearance levels.
pH of urine – important in urinary tract infections, control of nephrolithiasis treatment. pH is measured in a spontaneous urine portion at least 6 times for 24h, as well as after each meal and at night time and a 24 h curve of pH is plotted. Alkaline pH >7-8: in urinary tract infections Acidic pH <5: in diabetic ketosis, cardiac failure, starvation gout renal tuberculosis
Urine protein range <150 mg/24h —The measurement of proteinuria is obligatory in renal pathology. Possible parenchymal renal disease if >1g/24h protein found in the urine.
Glomerular filtration rate (eGFR)—a blood creatinine test. GFR refers to the amount of blood that is filtered by the glomeruli per minute. As a person's kidney function declines due to damage or disease, the filtration rate decreases and waste products begin to accumulate in the blood.
Blood Urea test (serum male 3,2 - 8,2 mmol/l, female 2,6 - 7,2 mmol/l) performed patients on haemodialysis, patients with acute and chronic renal failure (ARF and CRF), control of food protein intake in patients with CRF. A high Urea value can mean kidney injury or disease is present. Kidney damage can be caused by diabetes
- Uraemia – high levels of urea in the serum – above 50 mmol/l.
- Azotaemia is a medical condition characterized by abnormally high levels of nitrogen-containing compounds, such as urea, creatinine, various body waste compounds.
- Disadvantage: NPN in plasma depends on diet + functional state of the liver and kidneys